This application claims the priority of Korean Patent Application No. 2003-35302, filed on Jun. 2, 2003, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a high density magnetoresistance memory and a manufacturing method thereof, and particularly, to a magnetoresistance memory and a manufacturing method thereof for achieving high selectivity.
2. Description of the Related Art
FIG. 1 is a view of a conventional magnetic random access memory (MRAM) array. Referring to FIG. 1, the conventional MRAM stores information by reversing the magnetization direction of a memory cell 5 located between a digit line 1 and a bit line 3 using a magnetic field generated on the digit line 1 and the bit line 3 to which electric current is applied. However, the magnetic field generated due to the electric current applied to the digit line 1 and the bit line 3 may affect memory cells 7 and 9 located around the memory cell 5 which is at a point where the digit line 1 and the bit line 3 cross each other. Especially, in a memory cell that has gradually become compact and has a high memory density, coercivity of the memory cell increases and a current value required to reverse the magnetization direction also increases. Thus, the magnetic field affects the peripheral cells 7 and 9 beside the memory cell 5 and reverses the magnetization direction, thereby possibly increasing mis-operation of the memory.
To solve the above disadvantages of the MRAM, FIG. 2 shows an example of a conventional magnetoresistance memory having a structure capable of concentrating flux onto a memory cell. FIG. 2 is a cross-sectional view of an MRAM disclosed in U.S. Pat. No. 5,659,499.
Referring to FIG. 2, MRAM 35 comprises a substrate 11 and a memory cell 14 in which information is stored as a magnetization vector on the substrate 11. The memory cell 14 is made of a magnetoresistive (MR) material having a multi-layer structure including an insulating layer between magnetic materials, and having a length 21 (L) designated by an arrow and a width perpendicular to the ground. A column conductive material 12 is used to connect the memory cell 14 of a column shape to another memory cell. A dielectric material 13 is applied on the memory cell 14 and the conductive material 12 so as to insulate them from a conductive material 36 of the digit line. The conductive material 36 of the digit line is arranged to cross the memory cell 14 at a right angle. High-permeability materials 17 and 18 are applied on an upper surface and a side surface of the conductive material 36, which is on the digit line to change the magnetization direction according to the electric current applied to the digit line conductive material 36 and to focus the magnetic field onto the magnetic material in the memory cell 14. High-permeability materials 31 and 32 are formed on left and right upper portions of the memory cell 14 as strips to support the flux focusing function of the high-permeability materials 17 and 18. A distance 37 between the high permeable materials 32 and 33 is formed to be smaller than the width of the memory cell 14.
U.S. Pat. No. 6,174,737 also discloses an improved MRAM and manufacturing method thereof similar to the MRAM structure disclosed in U.S. Pat. No. 5,659,499. However, the conventional conductive layer for focusing the flux is formed as a stripe pattern on an upper portion of the bit line or the digit line to distribute the flux on a portion where the memory cell is not located, and thus, the flux cannot be focused effectively on the desired memory cell. Also, the stripe pattern should be fabricated after forming the memory cell, and therefore, it is not easy to perform the manufacturing processes.